Amyloid deposition in thymic extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue in a patient with myasthenia gravis: A case report.

Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT) in the thymus is a rare disease. Furthermore, amyloid deposition in thymic MALT lymphoma has not been previously described. Here, we report a case of a 35-year-old man with thymic MALT lymphoma with amyloid deposition and myasthenia gravis. Chest computed tomography revealed an anterior mediastinal mass with internal cystic component and extensive calcification. Total thymectomy was performed and histopathologic findings were compatible with a diffuse amyloid deposition in extranodal marginal zone MALT lymphoma. The results indicate that thymic MALT lymphoma should be considered as a possible diagnosis in patients with a solid and cystic thymic mass and autoimmune disease, including myasthenia gravis.